• Generally shorter(*) bootloaders given the same features
• New feature U which updates flash, ie, only changes flash when new content is different (less wear and faster)
• Pre-compiled bootloaders in urboot.hex

(*) The way urboot is compiled tends to fill out unused space with frills so that shorter code isn't readily visible, but it is

u7.7 with corrected rjmp opcode to pgm_write_page() bootloader function

This is the first public release of urboot that has been around since 2016. Urboot is a feature-rich small AVR bootloader using urprotocol with tight code (roughly half the size of optiboot), a highly modular feature set and direct support by AVRDUDE v7.1 onwards through its avrdude -c urclock programmer.